It was reported that a CD44s ligand, hyaluronic acid, upregulates and activates nuclear factor erythroid 2‐related factor 2 (NRF2) in bovine articular chondrocytes and then activated NRF2 further induces the expression of antioxidant enzymes including GPX1.35 The CD44s‐induced activation of NRF2 was also observed in a doxorubicin‐resistant breast cancer cell line, which possesses CSC‐like characteristics and dominantly expresses CD44s.36 It was demonstrated that NRF2 activation protects the breast cancer cells from oxidative stress and anticancer drugs.36 This evidence concerns the gene GPX1 and breast cancer.